September 19, 2022

5 Tips for Healthy Fasting

Ease into it, stay hydrated and plan ahead

Person eating at table.

Just the thought of fasting may make you hungry. But going without food for a time — whether for health or religious reasons — can be good for you, says hepatologist Nizar Zein, MD.

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

“There’s actually a range of ways to fast,” he says. “Sometimes, fasting means avoiding certain types of food, like carbohydrates or fats. Other times, it just means reducing calories overall. Then, there’s the type of fasting when you don’t eat (or sometimes drink) at all for a day or more.”

Many religions promote some form of fasting as a spiritual exercise. And medical literature indicates fasting, in general, can:

“There also are theories that periodic fasting may help you live longer, boost brain function and prevent neurodegenerative disease,” Dr. Zein notes.

What to know before you start fasting

If you’re planning a fast in which you don’t eat at all, Dr. Zein recommends these five tips for maintaining your health and energy level.

1. Ease into it

Cut back on food and drink gradually for several days — or even weeks — before your fast. Otherwise, abruptly beginning a fast will be a shock to your body.

“Don’t eat three full meals a day with between-meal snacks and then suddenly stop eating one day,” Dr. Zein says. “If your body is used to regular refueling, you may have a hard time maintaining energy levels during a fast.”

And keep your sugar intake low as you’re heading into a fast. Loading up on cookies and sweet tea before your fast isn’t a good idea. You may feel full and satisfied at first, but when your blood sugar plummets an hour or two later, you may become extremely hungry and weak. To have enough energy for the long haul, fill up on complex carbohydrates (like pasta, rice and potatoes) and protein (like meat and beans).

2. Drink plenty of water

Some religious fasts restrict all food and beverages, including water, as part of the observation. If, however, the guidelines for your fast allow for consumption of water, staying hydrated will help you avoid dehydration, maintain your energy levels and lessen side effects like headaches, cramps and irritability.

Advertisement

3. Cut down on activity

“It’s not a good idea to do intense exercise when you’re not eating or drinking,” says Dr. Zein. “If you’re not planning to replenish nutrients for a while, preserve your energy for vital daily activities.”

4. Plan ahead for medications

Before fasting, talk to your doctor about how to take your medications. Some medications — such as for seizure disorders — are essential, and you shouldn’t stop taking them while fasting. Other medications should be taken with food. “When people have adverse outcomes from fasting, it’s often because they didn’t take their medications correctly,” states Dr. Zein.

5. Ease out of it

At the end of your fast, replenish your calories gradually. Rather than going on an eating binge right away, spread those calories over your next two meals. This is better because it will help you avoid rapid changes in blood sugar and the fatigue associated with consuming a large amount of food.

Is fasting healthy?

“Overall, fasting can be a healthy practice that I recommend for many people,” says Dr. Zein.

Even when following these tips, too much fasting can be dangerous, though, and fasting for too long may cause dehydration, mental stress and disrupted sleep. Also, there are different health benefits and risks associated with various kinds of fasts, based on what restrictions you’re following and for how long.

Fasting for religious reasons

It’s customary in some religions to fast entirely for a day, for a portion of certain days or to abstain from certain foods for an extended period of time.

Is it safe? Research shows that religious fasting has potential benefits for improving cholesterol, reducing oxidative stress and balancing energy.

Fasting for health reasons

Some diets recommend eliminating certain foods or restricting eating at certain times, both of which can be done in a healthy way, Dr. Zein says.

Advertisement

Intermittent fasting, for example, encourages people to only eat during certain times of the day or to restrict eating on certain days. It’s an eating pattern that focuses on consciously cutting back on calories for certain time periods.

Certain restrictive diets, like the ketogenic diet (keto), approach fasting differently. Rather than fasting for a period of time, people who follow keto cut all carbs and sugars from their diets.

Is it safe? Studies have shown intermittent fasting and certain restrictive diets can be good for your heart health, help with weight loss and improve your cholesterol. However, researchers also caution that fasting diets can be difficult to maintain as a long-term lifestyle.

Who shouldn’t fast?

While fasting can be done safely for some people, it can cause problems for people with certain health conditions.

Many religions indicate certain groups of people may not be required to participate in fasting based on certain criteria. From a health perspective, Dr. Zein suggests those who shouldn’t fast from all food and drink include people who:

Fasting may provide psychological and physical benefits when done in a healthy way. If you plan to make fasting a part of your routine, talk with a healthcare provider about any risks.

Related Articles

Small cup of yogurt with fresh blueberries on top, with mint sprig
March 1, 2024
Easy, Low-Calorie Snacks To Get You Through the Day

Snacking can bring benefits with healthy food choices and planning

Various cuts of red meat displayed
February 14, 2024
Is Red Meat Bad for You?

It has nutrients your body needs, but it also comes with some serious health risks

Meal prepping various dishes for snack, lunch and dinner
January 29, 2024
75 Healthy Meal Prep Ideas for Breakfast, Lunch and Dinner

No more scrambling to figure out what to eat during your busy week

Display of various types of foods prepped in individual containers
January 15, 2024
A Beginner’s Guide to Healthy Meal Prep

Set yourself up for success by carefully choosing your recipes, storage containers and prepping day

Closeup of roasted garlic tomato zucchini bake on a stoneware plate with grated cheese garnish
January 3, 2024
Recipe: Roasted Garlic, Zucchini and Tomato Bake

A colorful side dish to brighten any meal

cool tropical smoothie with straw
November 29, 2023
Recipe: Cool Tropical Smoothie

A zesty thirst-quencher that’s dairy-free and vegan

skillet of ground turkey stroganoff
November 27, 2023
Recipe: Healthy Turkey Stroganoff

A hearty dish that’s easy to put together

Overhead closeup of cauliflower pseudo mashed potatoes in a bowl on a wooden table.
November 20, 2023
Recipe: Cauliflower Mashed Pseudo Potatoes

A creamy mashed cauliflower that’s sure to please

Trending Topics

White bowls full of pumpkin seeds, dark chocolate and various kinds of nuts
25 Magnesium-Rich Foods You Should Be Eating

A healthy diet can easily meet your body’s important demands for magnesium

Woman feeling for heart rate in neck on run outside, smartwatch and earbuds
Heart Rate Zones Explained

A super high heart rate means you’re burning more than fat

Spoonful of farro salad with tomato
What To Eat If You’ve Been Diagnosed With Prediabetes

Type 2 diabetes isn’t inevitable with these dietary changes

Ad